import java.util.Scanner;

/**
 * Created by forcht on 2018/4/25.
 */
public class Main {

    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        String s1=scanner.next();
        String s2=scanner.next();
        StringBuilder n=new StringBuilder(s1);
        StringBuilder m=new StringBuilder(s2);
        n=n.reverse();
        m=m.reverse();
        boolean flag=false;
        int c=0;
        int i=0;
        int sum=0;
        StringBuilder s=new StringBuilder();
        while (i<n.length()&&i<m.length()){
            if(n.charAt(i)<'0'||n.charAt(i)>'9'||m.charAt(i)<'0'||m.charAt(i)>'9'){
                flag=true;
                break;
            }
            sum=n.charAt(i)-'0'+m.charAt(i)-'0'+c;
            c=sum/10;
            s.append(sum%10);
            i++;
        }
        if(n.length()>=m.length())m=n;
        while (i<m.length()){
            if(m.charAt(i)<'0'||m.charAt(i)>'9'){
                flag=true;
                break;
            }
            sum=m.charAt(i)-'0'+c;
            c=sum/10;
            s.append(sum%10);
            i++;
        }
        if (c>0)s.append(c);
        if(flag){
            System.out.println("Error");
        }else {
            System.out.println(s.reverse());
        }
    }
}
